Hot deformation behavior of as cast Al-3Mg-0.25Sc alloy

Deformation behavior of as-cast Al-3Mg-0.25Sc alloy was studied under compression at different strain rates ranging from 0.001 to 10s-1 in the temperature range 573-773 K. Processing maps were generated at different plastic strains to understand the deformation characteristics as a function of temperature and strain rate. Temperature jump tests were performed for determining thermal activation parameters needed to identify the rate controlling deformation mechanisms. The processing maps showed two safe regimes with high efficiency of power dissipation in the temperature range 573-623 K and 673-723 K at 0.001s-1. Microstructural investigation of the deformed samples confirmed these two regimes as dynamic recovery and dynamic recrystallization, respectively. The stress exponent (n~3-5) and apparent activation energy (Q~160-190 kJ.mol-1) values suggest that dislocation core diffusion and solute drag of gliding dislocations are the rate controlling mechanisms. The present study revealed that the optimum hot working regime for the as-cast Al-3Mg-0.25Sc alloy is 623-723 K and 0.001 s-1